兄弟连区块链教程btcpool矿池源码分析StratumServ

　　兄弟连区块链教程btcpool矿池源码分析StratumServer模块解析，2018年下半年，区块链行业正逐渐褪去发展之初的浮躁、回归理性，表面上看相关人才需求与身价似乎正在回落。但事实上，正是初期泡沫的渐退，让人们更多的关注点放在了区块链真正的技术之上。

    # btcpool矿池-StratumServer模块解析

##核心机制总结

*接收的job延迟超过60秒将丢弃

*如果job中prevHash与本地job中prevHash不同，即为已产生新块，job中isClean状态将置为true

* true即要求矿机立即切换job

*三种情况下将向矿机下发新job：

*收到新高度的job

*过去一个job为新高度且为空块job，且最新job为非空块job

*达到预定的时间间隔30秒

*最近一次下发job的时间将写入文件（由file_last_notify_time指定）

*本地job有效期为300秒

*每10秒拉取一次新用户列表（由list_id_api_url指定），用户写入本地map中

* sserver最大可用SessionId数为16777214

* btcpool支持BtcAgent扩展协议和Stratum协议，使用magic_number（0x7F）区分

*处理Stratum协议：

* suggest_target与suggest_difficulty等价，用于设置初始挖矿难度，需在subscribe之前请求

*使用sessionID作为extraNonce1_以确保矿机任务不重复

* authorize之前有15秒读超时，authorize之后有10分钟读超时，10分钟无提交将断开连接

*初始难度为16384，或从suggest_difficulty指定，下次将一次调整到位保持10s提交share

*每个session会维护一个localJobs_队列，队列长度为10条

* share被拒绝的几种情况：

* JOB_NOT_FOUND，localJobs_队列中该job已被挤出

* DUPLICATE_SHARE，share已提交过，已提交的share会计入submitShares_

* JOB_NOT_FOUND，jobRepository_中job不存在，即job已过期（300秒过期时间）

* JOB_NOT_FOUND，jobRepository_中job状态为Stale，即job是旧的非新job

* TIME_TOO_OLD，share中提交的nTime小于job规定的minTime

* TIME_TOO_OLD，share中提交的nTime比当前时间大10分钟

* LOW_DIFFICULTY，share中提交的hash不满足难度目标

*处理BtcAgent扩展协议：

* Agent下矿机默认难度也为16384

*使用Agent sessionID作为extraNonce2_前半部分，以确保Agent下矿机任务不重复

*矿池下发新任务时，如session为BtcAgent，将为Agent下所有矿机计算难度

*如难度发生变更，将按难度不同，分别构造多条CMD_MINING_SET_DIFF指令一并下发处理

## StratumServer命令使用

```shell

sserver -c sserver.cfg -l log_dir

#-c指定sserver配置文件

#-l指定日志目录

```

## sserver.cfg配置文件

```shell

//是否使用testnet

testnet = true;

//kafka集群

kafka = {

brokers = "1.1.1.1:9092,2.2.2.2:9092,3.3.3.3:9092";

};

//sserver配置

sserver = {

//IP和端口

ip = "0.0.0.0";

port = 3333;

//server id，全局唯一，取值范围[1, 255]

id = 1;

//最近一次挖矿通知时间写入文件，用于监控

file_last_notify_time = "/work/xxx/sserver_lastnotifytime.txt";

//如果启用模拟器，所有share均被接受，用于测试

enable_simulator = false;

//如果启用，所有share都将成块并被提交，用于测试

enable_submit_invalid_block = false;

//两次share提交的间隔时间

share_avg_seconds = 10;

};

users = {

//用户列表api

list_id_api_url = "example.com/get_user_id_list";

};

```

## SOLVED_SHARE消息

```c++

if (isSubmitInvalidBlock_ == true || bnBlockHash <= bnNetworkTarget) {

    //

    // build found block

    //

    FoundBlock foundBlock;

    foundBlock.jobId_ = share.jobId_;

    foundBlock.workerId_ = share.workerHashId_;

    foundBlock.userId_ = share.userId_;

    foundBlock.height_ = sjob->height_;

    memcpy(foundBlock.header80_, (const uint8_t *)&header, sizeof(CBlockHeader));

    snprintf(foundBlock.workerFullName_, sizeof(foundBlock.workerFullName_),

        "%s", workFullName.c_str());

    // send

    sendSolvedShare2Kafka(&foundBlock, coinbaseBin);

    // mark jobs as stale

    jobRepository_->markAllJobsAsStale();

    LOG(INFO) << ">>>> found a new block: " << blkHash.ToString()

    << ", jobId: " << share.jobId_ << ", userId: " << share.userId_

    << ", by: " << workFullName << " <<<<";

}

```

##计算挖矿难度

```c++

//构造函数

//kMinDiff_为最小难度，static const uint64 kMinDiff_ = 64;

//kMaxDiff_为最大难度，static const uint64 kMaxDiff_ = 4611686018427387904ull;

//kDefaultDiff_为默认初始难度，static const uint64 kDefaultDiff_ = 16384;

//kDiffWindow_为N个share的时间窗口，static const time_t kDiffWindow_ = 900;

//kRecordSeconds_为1个share的时间，static const time_t kRecordSeconds_ = 10;

//sharesNum_和shares_初始值均为90

DiffController(const int32_t shareAvgSeconds) :

    startTime_(0),

    minDiff_(kMinDiff_), curDiff_(kDefaultDiff_), curHashRateLevel_(0),

    sharesNum_(kDiffWindow_/kRecordSeconds_), /* every N seconds as a record */

    shares_ (kDiffWindow_/kRecordSeconds_)

{

    if (shareAvgSeconds >= 1 && shareAvgSeconds <= 60) {

        shareAvgSeconds_ = shareAvgSeconds;

    } else {

        shareAvgSeconds_ = 8;

    }

}

//代码btcpool/src/StratumSession.h

//计算挖矿难度

//不低于最小难度64

uint64 DiffController::calcCurDiff() {

uint64 diff = _calcCurDiff();

if (diff < minDiff_) {

diff = minDiff_;

}

return diff;

}

uint64 DiffController::_calcCurDiff() {

const time_t now = time(nullptr);

const int64 k = now / kRecordSeconds_;

const double sharesCount = (double)sharesNum_.sum(k);

if (startTime_ == 0) { // first time, we set the start time

startTime_ = time(nullptr);

}

const double kRateHigh = 1.40;

const double kRateLow = 0.40;

//时间窗口（900秒）内预期的share数

double expectedCount = round(kDiffWindow_ / (double)shareAvgSeconds_);

//return now >= startTime_ + kDiffWindow_;

if (isFullWindow(now)) { /* have a full window now */

// big miner have big expected share count to make it looks more smooth.

expectedCount *= minerCoefficient(now, k);

}

if (expectedCount > kDiffWindow_) {

//最多1秒提交1个，预期share数最大为900

expectedCount = kDiffWindow_; // one second per share is enough

}

// this is for very low hashrate miner, eg. USB miners

// should received at least one share every 60 seconds

//非完整时间窗口、且时间已超过60s、提交的share数小于（60秒1个）、当前难度大于或等于2倍最小难度

//此时降低难度为之前1/2

if (!isFullWindow(now) && now >= startTime_ + 60 &&

sharesCount <= (int32_t)((now - startTime_)/60.0) &&

curDiff_ >= minDiff_*2) {

setCurDiff(curDiff_ / 2);

sharesNum_.mapMultiply(2.0);

return curDiff_;

}

// too fast

//如果提交share数超过预期数的1.4倍时

if (sharesCount > expectedCount * kRateHigh) {

//如果share数大于预期share数，且当前难度<最大难度时，提升难度为原来2倍

while (sharesNum_.sum(k) > expectedCount &&

curDiff_ < kMaxDiff_) {

setCurDiff(curDiff_ * 2);

sharesNum_.mapDivide(2.0); //share数/2

}

return curDiff_;

}

// too slow

//如果是完整时间窗口，且当前难度大于或等于2被最小难度

if (isFullWindow(now) && curDiff_ >= minDiff_*2) {

//如果share数低于预期数的0.4，且当前难度大于或等于2倍最小难度，降低难度为原来的1/2

while (sharesNum_.sum(k) < expectedCount * kRateLow &&

curDiff_ >= minDiff_*2) {

setCurDiff(curDiff_ / 2);

sharesNum_.mapMultiply(2.0); //share数乘2

}

assert(curDiff_ >= minDiff_);

return curDiff_;

}

return curDiff_;

}

```

## sserver校验share的机制

```shell

//本地job列表localJobs_最多保留最近10条任务，如有新任务，将挤出1条老任务。如果share所对应的job未在本地列表中，将StratumError::JOB_NOT_FOUND

//本地share列表submitShares_中，如果已有本条share，即重复，将StratumError::DUPLICATE_SHARE

//校验share不通过

//　　job列表exJobs_没有找到job，exJobs_中job有300秒过期时间，过期将删除，报StratumError::JOB_NOT_FOUND

//　　share中nTime小于job的最小时间，过老，报StratumError::TIME_TOO_OLD

//　　share中nTime超过job中的nTime 10分钟，过新，报StratumError::TIME_TOO_NEW

//　　区块哈希>job难度目标，不合格，报StratumError::LOW_DIFFICULTY

```

## sserver下发新job的机制

1、如果收到新高度statum job，将立即下发新job

```c++

bool isClean = false;

if (latestPrevBlockHash_ != sjob->prevHash_) {

    isClean = true;

    latestPrevBlockHash_ = sjob->prevHash_;

    LOG(INFO) << "received new height statum job, height: " << sjob->height_

    << ", prevhash: " << sjob->prevHash_.ToString();

}

shared_ptr<StratumJobEx> exJob = std::make_shared<StratumJobEx>(sjob, isClean);

{

    ScopeLock sl(lock_);

if (isClean) {

        // mark all jobs as stale, should do this before insert new job

        for (auto it : exJobs_) {

            it.second->markStale();

        }

    }

    // insert new job

    exJobs_[sjob->jobId_] = exJob;

}

if (isClean) {

    sendMiningNotify(exJob);

    return;

}

```

2、如果过去一个job为新高度且为空块job，并且最新job非空块job，将尽快下发新job

```

if (isClean == false && exJobs_.size() >= 2) {

    auto itr = exJobs_.rbegin();

    shared_ptr<StratumJobEx> exJob1 = itr->second;

    itr++;

    shared_ptr<StratumJobEx> exJob2 = itr->second;

    if (exJob2->isClean_ == true &&

        exJob2->sjob_->merkleBranch_.size() == 0 &&

        exJob1->sjob_->merkleBranch_.size() != 0) {

        sendMiningNotify(exJob);

    }

}

```

3、每超过一定时间间隔（30秒），将下发新job

```

void JobRepository::checkAndSendMiningNotify() {

    // last job is 'expried', send a new one

    if (exJobs_.size() &&

        lastJobSendTime_ + kMiningNotifyInterval_ <= time(nullptr))

    {

        shared_ptr<StratumJobEx> exJob = exJobs_.rbegin()->second;

        sendMiningNotify(exJob);

    }

}

JobRepository::JobRepository(const char *kafkaBrokers,

    const string &fileLastNotifyTime,

    Server *server):

running_(true),

kafkaConsumer_(kafkaBrokers, KAFKA_TOPIC_STRATUM_JOB, 0/*patition*/),

server_(server), fileLastNotifyTime_(fileLastNotifyTime),

kMaxJobsLifeTime_(300),

kMiningNotifyInterval_(30), // TODO: make as config arg

lastJobSendTime_(0)

{

    assert(kMiningNotifyInterval_ < kMaxJobsLifeTime_);

}

更多区块链技术分享：https://ke.qq.com/course/334561